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About Water Quality

In the UK DEFRA (the Department for Environment, Food and Rural Affairs) is responsible for all aspects of water policy, including water supply and resources.

These include:

  • drinking water quality

  • the quality of water in rivers, lakes and estuaries, coastal and marine waters

  • sewage treatment; and

  • reservoir safety.

The Environment Agency (EA) monitor the water quality at over 7,000 inland sites, representing about 40,000km of rivers and canals and 2,800km of estuaries in England and Wales.

Statistical methods are used in the General Quality Assessment (GQA) scheme for rivers and for the classification of estuaries, taking in:

  • Chemical quality of rivers - dissolved oxygen, oxygen demand and ammonia.

  • Biological quality of rivers - using macro-invertebrates.

  • Nutrient status of rivers - phosphate and nitrate.

  • Aesthetic quality of rivers - litter, foam, odour and colour.

  • Estuary quality - biological, chemical and aesthetic quality.

The quality of bathing waters in England and Wales is monitored against standards laid down in the bathing water regulations (SI 1991/1597), which come from the EC Bathing Water Directive (76/160/EEC).

Compliance with the EC Bathing Water Directive standards is assessed annually by DEFRA on the basis of information supplied by the the EA.  The Bathing Water Directive sets out two levels of standards, those that must be complied with - Mandatory (or Imperative) standards - and the more stringent Guideline standards that Member States should strive to achieve. The Government has set the Environment Agency a Public Service Agreement (PSA) target of 97% Mandatory compliance and 85% Guideline compliance by 2005.

The EA monitors the quality of 473 designated coastal and nine inland (lakes and rivers) bathing waters throughout England and Wales (figures for 2000).  The bathing season is taken to be from 15 May to 30 September.  Water sampling begins two weeks before the start of the season (i.e. 01 May) and 20 samples are taken (essentially one a week) throughout the season.  All sampling is undertaken at pre-determined points on the beach, where the daily average density of bathers has been considered to be at its highest.  Water samples are taken at a depth of approx. 30cm below the surface; additional surface samples may be taken to test for the presence of mineral oils.

Each sample is tested for total coliform bacteria and for faecal coliform bacteria.  Faecal coliform bacteria are an indicator of the presence of traces of human sewage.  

Analysis of bathing waters are also made on the basis of other standards in the EC Directive. Two samples are analysed for the presence of enteroviruses, and two for the presence of salmonellae, at any site which had failed the mandatory coliform standards in the previous year.

Because the quality on a number of bathing waters is on the borderline between compliance and non-compliance, there is always a statistical risk that some of them will 'pass' in one year and 'fail' in another even though their actual quality has not significantly changed.  Real changes in quality can also occur from year to year simply as a result of differences in the weather.

The results of the various bathing water analyses are used to assist in giving "awards" to bathing beaches, such as the Blue Flag.

  • Detailed compliance figures for coastal and inland bathing waters can be found at the EA web site - click here for a visit.


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